Pig foaming at the mouth

Foaming at the corners of a pig's mouth is a stereotypical behavior of pretending to chew.
When pigs feel uncomfortable,
Stereotyped behavior can stimulate the secretion of morphine-like substances,
Used to soothe anxious and anxious situations,
Think of foaming as a sign of a yellow light.
If many pigs in the farm continue to exhibit false chewing behavior,
You should try to find out the cause from feed, environment, and physiological symptoms.